unable to add App Project into testServer

hi, any one have idea why?

I have a j2ee project. also a server project, inside it is the Server1(which i have already configured with a data source - db2).

I right-click the server and 'add' the project.

but when i 'run on server', it says that no server is linked to it,

...and the already running 'Server1', seems to be invisible, such that it starts another instance of that already running server when i choose to link it to the project when attempting to run the project.

any have any idea on this?